Chronic pain affects over 100 million Americans, with an annual cost estimated at over $500 billion. Reliance on opioid medications has led to an ?opioid crisis? and the need to identify alternative treatment for chronic pain. The proposed project hypothesizes that chronic pain represents failure or suboptimal function of pain modulatory capacity (PMC). The proposed project aims to test hypotheses about resilience to clinically relevant pain challenges, and test multisystem (psychological, behavioral, and neural) mechanisms underlying chronic pain. Furthermore, the project aims to demonstrate the trainability of PMC in asymptomatic controls, which has relevance for pain prevention, and in patients with fibromyalgia (FM) who are hypothesized to have suboptimal PMC (resilience) to pain challenges. We will test hypotheses about the trainability of endogenous pain modulation based on similar processes seen in other physiological systems. The research is highly innovative and challenges common (and unsuccessful) conceptualizations of pain treatment and variability. A typical target of pain treatment is reduction of pain variability, which we argue is erroneous. We hypothesize that pain variability is a marker for PMC and treatment should focus on increasing this capacity rather than eliminating it. Demonstration of the modifiability of PMC will have direct translation to both prevention of chronic pain and treatment of chronic pain. !